<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8">
    <title>Document</title>
  </head>
  <body>
    手机号码： <input type="number"> <button>发送</button>
    <script>
      var btn = document.querySelector('button');
      var time = 60;    // 定义剩下的秒数
      btn.addEventListener('click', function () {
        btn.disabled = true;
        var timer = setInterval(function () {
          if (time == 0) {
            clearInterval(timer);
            btn.disabled = false;
            btn.innerHTML = '发送';
          } else {
            btn.innerHTML = '还剩下' + time + '秒';
            time--;
          }
        }, 1000);
      })
    </script>
  </body>
</html>